Pressure sensor, strain gauge and method for producing a strain gauge

Abstract

The present invention relates to a strain gauge (100, 120, 130, 140) which comprises a substrate (10, 12, 14), a nanogranular sensor element (20) deposited on the substrate (10, 12, 14) and at least two electrodes (30, 12), which are electrically connected to the sensor element (20) in order to enable measurement of strain-dependent changes in the conductivity of the sensor element (20).

Description

[0001] PRESSURE SENSOR, STRENGTH SENSOR AND METHOD FOR MANUFACTURING A STRENGTH SENSOR

[0002] Technical field

[0003] The present disclosure relates to strain sensors capable of performing precise strain measurements and adaptable to various substrates, as well as to a method for manufacturing such strain sensors.

[0004] State of the art

[0005] Strain gauges are devices that measure strain using various principles. Today, a wide variety of strain gauges with different properties are available for diverse applications.

[0006] Description of the invention

[0007] Starting from the known state of the art, it is an object of the present invention to provide an improved pressure sensor and an improved strain sensor, as well as a corresponding method for their manufacture.

[0008] The problem is solved by a pressure sensor with the features of claim 1. Advantageous further developments are described in the dependent claims, the detailed description, and the figures.

[0009] Accordingly, a pressure sensor is proposed comprising a substrate with a pressure-sensing membrane. At least one nanogranular sensor element is deposited on the membrane. The pressure sensor further comprises at least two electrodes electrically connected to the sensor element to enable the measurement of pressure-induced conductivity changes of the sensor element.

[0010] A pressure-sensitive membrane can be understood as a thin, flexible structure capable of deforming under the influence of pressure differences. The membrane can be designed so that one side is exposed to the pressure to be measured, while the other side serves as a reference. The deformation of the membrane caused by the pressure difference can then be converted into a measurable electrical signal by the nanogranular sensor element. The sensitivity and measuring range of the membrane can be influenced by its geometry, thickness, and material properties. In this context, the term "nanogranular sensor element" means that the sensor element consists of, or at least incorporates, a nanogranular material.Nanogranular materials offer the advantage that the measurable strain range of the sensor element can be precisely controlled by adjusting the shape, morphology, material, spacing, and number of grains. In particular, the grains can be embedded in a dielectric matrix. The various conductivity mechanisms arise from the different regimes of the conductivity phase diagram. For example, thermally activated transport processes dominate in the Arrhenius regime, while different tunneling processes dominate in the inelastic and elastic co-tunneling regimes. Metallic transport dominates in the granular Fermi fluid regime, whereas in the universal behavior regime, conductivity is independent of specific system details.

[0011] In other words, a nanogranular sensor element comprises an ensemble of electrically conductive grains in the nanometer range, whose electrical transport properties are determined by their conductivity, size, spacing, and the matrix material. Sensitivity to temperature or radiation arises in particular from effects such as variable range hopping and thermally activated transport.

[0012] In other words, a material described in the literature as nanogranular comprises an ensemble of charge carrier centers that exist in different geometric configurations within at least one matrix material or a mixture of different matrix materials. These charge carrier centers can be distributed homogeneously or inhomogeneously within the matrix material. The electrical transport properties can be determined by material properties (charge carrier density, band structure, and, if applicable, electrical defects due to crystal flaws within the charge carrier centers), the geometric configuration of the charge carrier centers, and their spacing within the matrix.The physical properties of the matrix material (lattice configuration, crystal structure, material) and the individual transition between the matrix material and the individual charge carrier center (transition of the charge carrier center's ligand shell to the matrix, defects) also define the conductivity properties in the nanogranular material. Impurities in the charge carrier centers and in the matrix material also represent defects (essentially, all grain boundaries in the metal, in the matrix, and between the materials, as well as potentially between the materials themselves, are impurities) that are important for charge carrier transport. Furthermore, the interfaces of the nanogranular material with the continuum play a role in defining the conductivity. In some embodiments, the membrane delineates a cavity introduced into the substrate.This cavity can be sealed gas-tight from the environment and in some cases may have a negative pressure relative to the environment.

[0013] Due to the constant negative pressure, this cavity serves as the reference or reference pressure for the membrane, so that the membrane is subjected to the pressure to be measured on one side, while the negative pressure serves as a fixed reference on the other. This ensures that the mechanical deformation behavior of the membrane due to a pressure difference can be reliably reproduced.

[0014] In some embodiments, the membrane can have a planar extent of 1–500 pm by 1–500 pm, and in some cases, 25 pm by 25 pm. The membrane thickness can range from 5 nm to 50 nm, and in some embodiments, from 8–12 nm.

[0015] The size and shape of the diaphragm can vary in different designs to optimize the sensitivity of the pressure sensor for specific applications. While a square or rectangular diaphragm can be used in some cases, other geometric shapes are also possible. For example, the diaphragm can be circular, elliptical, or even have an irregular organic shape.

[0016] The choice of diaphragm size and shape can affect several aspects of sensor behavior. A larger diaphragm area can, in some cases, lead to higher sensitivity because it allows for greater deformation at the same pressure change. Smaller diaphragms, on the other hand, can be advantageous in some applications where higher spatial resolution or a faster response time is required.

[0017] Circular diaphragms can exhibit a more uniform stress distribution across their surface in certain situations, which can lead to a linear response. Elliptical or asymmetrical diaphragm shapes can, in some cases, be used to enable direction-dependent pressure measurements or to increase sensitivity in specific directions.

[0018] The choice of membrane geometry can also be influenced by factors such as available space, manufacturing processes, or the specific requirements of the application. In some cases, more complex membrane shapes can be used to achieve specific resonant frequencies or to optimize sensitivity in certain pressure ranges. In further embodiments, at least four nanogranular sensor elements can be deposited on the substrate. Two of these sensor elements can be deposited in a region within the membrane, forming a second and third bridge resistor. The two remaining sensor elements can form a first and fourth bridge resistor. These four bridge resistors can be connected via a bridge circuit.

[0019] The use of a bridge circuit in conjunction with nanogranular sensor elements can significantly improve the performance and accuracy of the pressure sensor. The bridge circuit enables differential measurement, where small changes in resistance can be converted into larger changes in voltage. This can increase the sensor's sensitivity while simultaneously compensating for unwanted effects such as temperature fluctuations or electromagnetic interference. In some cases, the bridge circuit can also contribute to linearizing the sensor's response and simplifying signal processing.

[0020] The two additional nanogranular sensor elements can be deposited in the area of ​​the membrane's edge.

[0021] The arrangement of the two additional nanogranular sensor elements at the membrane's edge enables differentiated detection of the membrane's deformation profile. This configuration can help capture the different deformation characteristics between the center and the membrane's periphery. In some cases, this can lead to more precise pressure measurements, as the periphery may respond differently to pressure changes than the center. By combining sensor elements at the center and edge of the membrane, a more comprehensive and balanced measurement of membrane deformation can be achieved in some embodiments. This can improve the overall accuracy and reliability of the pressure sensor and, in some applications, allow for a more detailed analysis of the pressure distribution across the entire membrane surface.

[0022] The four nanogranular sensor elements can be arranged in a plane traversing the membrane and / or along a line passing through the membrane.

[0023] In this way, the expansion behavior of the membrane can be reliably read out.

[0024] The width of each nanogranular sensor element can range from 1 nm to 500 nm, in some cases from 200 nm to 400 nm or from 8 nm to 12 nm. The height of each nanogranular sensor element can range from 1 nm to 100 nm, in some embodiments from 1 nm to 12 nm. The length of each nanogranular sensor element can also range from 1 nm to 100 nm, in some cases from 8 nm to 12 nm. The specific dimensions of the nanogranular sensor elements can have various effects on the performance and characteristics of the pressure sensor. The nanometer dimensions enable high sensitivity to even the smallest deformations of the membrane, which can contribute to precise pressure measurement. In some cases, the small size of the sensor elements can lead to an improved signal-to-noise ratio because thermal noise is reduced.Varying the dimensions within the specified ranges allows for the optimization of sensor characteristics for specific applications. For example, thinner sensor elements may exhibit higher strain sensitivity in some cases, while wider elements may offer better electrical conductivity. The ability to adjust the size of the sensor elements can also facilitate integration into various membrane sizes and shapes, thus increasing the flexibility of the sensor design.

[0025] The problem is further solved by a strain sensor with the features of claim 8. Advantageous further developments result from the dependent claims, the description, and the figures.

[0026] Accordingly, a strain sensor is proposed comprising a substrate on which a nanogranular sensor element is deposited. The strain sensor further includes at least two electrodes electrically connected to the sensor element to enable the measurement of strain-dependent conductivity changes of the sensor element.

[0027] The strain sensor offers exceptional versatility and adaptability. By varying the size, shape, and composition of its nanogranular structure, the sensor can be optimized for diverse applications and measurement ranges. Integrating the sensor element onto a substrate with electrical contacts allows for easy implementation in various systems and devices. Furthermore, the sensor's sensitivity and response can be precisely controlled by modifying the nanogranular structure, enabling a customized solution for specific measurement tasks.

[0028] The sensor element can be in direct contact with the substrate, with an insulating layer potentially positioned between a first electrode and the substrate. In some cases, the electrically non-insulating substrate can form a second electrode.

[0029] In some embodiments, the sensor element may be encapsulated with a cover layer. The strain sensor may comprise a bridge circuit, wherein at least one sensor element may be a measuring resistor. The bridge circuit may, in some cases, be a 1 / 4 bridge, a 1 / 2 bridge, or a 4 / 4 bridge.

[0030] The aforementioned problem is also solved by a method for manufacturing a strain sensor with the features of claim 14. Advantageous embodiments are described in the dependent claims, the description, and the figures.

[0031] Accordingly, a method for manufacturing a strain sensor is proposed. This method can include providing a substrate, providing at least two electrodes, depositing a nanogranular sensor element on the substrate, and connecting the sensor element to the at least two electrodes.

[0032] In some embodiments, the step of depositing the sensor element may include masking the deposition site for the sensor element, depositing the sensor element using various techniques such as pulsed laser deposition, laser evaporation, cluster deposition, sputtering or co-sputtering, and removing the mask.

[0033] In other embodiments, the sensor element can be deposited using Electron Beam Induced Deposition (EBID) or Focused Ion Beam Deposition.

[0034] In some cases, the deposited sensor element can be post-processed, which can alter the crystal structure and / or grain structure. This post-processing can include annealing, in particular local laser annealing.

[0035] The problem is also solved by a medical instrument with the features of claim 19. Advantageous further developments result from the dependent claims, the description, and the figures.

[0036] Accordingly, a medical instrument is proposed that includes a treatment head for treating a patient and a pressure sensor and / or strain sensor arranged on the treatment head.

[0037] Integrating pressure or strain sensors into medical instruments offers numerous advantages for clinical practice. Precisely measuring the forces applied by the practitioner enables improved control during medical procedures, which is particularly crucial when treating delicate tissues or working near critical structures. Real-time feedback on applied forces or pressures increases treatment precision while simultaneously reducing the risk of unintentional tissue damage. The adaptability of nanogranular sensor elements allows them to be manufactured in various sizes and shapes, enabling their integration into diverse medical instruments without significantly impacting their functionality or handling.

[0038] The sensors' small size represents another significant advantage, as it allows for integration even into very small or delicate medical instruments, which is particularly beneficial in minimally invasive surgery. The ability to measure and document applied forces or pressures enables standardized and reproducible treatments, which is relevant for both quality assurance and research purposes. Furthermore, medical training can be improved through the use of sensor-equipped instruments, as trainees receive objective feedback on their technique. The ability to detect and avoid excessive forces or pressures contributes to increased patient safety.

[0039] The applications for pressure and strain sensors in the medical field are diverse and encompass various specialties. In surgery, these sensors can be integrated into instruments such as scalpels, forceps, or endoscopes to monitor and optimize the forces applied by the surgeon. In interventional cardiology or radiology, sensors embedded in catheters or guidewires facilitate navigation through blood vessels and minimize the risk of vascular injury. These sensors are also used in dentistry, where they help ensure optimal force is applied during treatment using drills or implantation tools.

[0040] In orthopedics, sensor-equipped instruments support precise positioning and force application during joint replacement surgery or fracture fixation. In rehabilitation medicine, sensors integrated into training devices allow for the measurement of stress on joints or muscles and contribute to the optimal dosage of exercises. In needle-based procedures such as biopsies or injections, sensors can support correct placement and pressure application. In robot-assisted surgery, these sensors significantly improve haptic feedback for the surgeon.

[0041] Other important areas of application include wound care, where pressure sensors in dressings or compression therapy devices can ensure optimal pressure, and respiratory therapy, where sensors integrated into masks or tubes enable precise monitoring and control of airway pressure. In ophthalmology, sensors help to accurately measure and control intraocular pressure during eye surgery or tonometry. All these applications contribute to making medical procedures more precise, safer, and more efficient by providing objective measurement data in real time, thus significantly supporting decision-making and treatment quality.

[0042] In some embodiments, the nanogranular sensor element can be deposited directly on the treatment head as a substrate.

[0043] This invention thus provides improved pressure and strain sensors and methods for their manufacture, which can be used in various applications, including medical instruments.

[0044] Brief description of the characters

[0045] Preferred further embodiments of the invention are explained in more detail by the following description of the figures. These show:

[0046] Figure 1 shows a schematic cross-sectional view of a first embodiment of a strain sensor, wherein the sensor element is applied and encapsulated on an insulating substrate and is electrically contacted via electrodes.

[0047] Figure 2 shows a schematic cross-sectional view of a strain sensor in a second embodiment, wherein the sensor element is applied to an electrically non-insulating substrate and an insulating layer is provided between the electrodes and the non-insulating substrate.

[0048] Figure 3 shows a schematic cross-sectional view of a strain sensor in a third embodiment, wherein the sensor element is applied to an electrically non-insulating substrate and an insulating layer is provided between the non-insulating substrate and one of the electrodes.

[0049] Figure 4 shows a schematic cross-sectional view of a strain sensor in a fourth embodiment, wherein the sensor element is applied to an electrically non-insulating substrate and an insulating layer is provided between one of the electrodes and the non-insulating substrate. Figures 5A, B, and C show various schematic embodiments of layouts of a strain sensor in which a sensor element is contacted with two pairs of electrodes for voltage-correct measurement.

[0050] Figure 6 shows a schematic diagram of the measuring circuit, which is operated by

[0051] Strain sensor of figures 5A-5C is provided,

[0052] Figure 7 shows a schematic diagram of a Wheatstone

[0053] Bridge configuration with integrated strain sensor,

[0054] Figure 8 shows a schematic diagram of a high-precision strain sensor incorporating a Wheatstone bridge configuration,

[0055] Figure 9 shows a schematic diagram of a high-precision strain sensor, which includes a Wheatstone bridge configuration in a further representation,

[0056] Figure 10 shows a schematic cross-sectional view of a pressure sensor in which four nanogranular sensor elements are arranged in one plane on a pressure-sensitive membrane,

[0057] Figure 11 shows a schematic diagram of a high-precision pressure sensor comprising a Wheatstone bridge configuration of the four nanogranular sensor elements shown schematically in Figure 10,

[0058] Figure 12 shows a schematic enlarged top view of the pressure sensor from Figure 10, in which the pressure-sensitive membrane and the nanogranular sensor elements arranged on the pressure-sensitive membrane are shown schematically.

[0059] Figure 13 schematically shows a top view of the pressure sensor from Figure 12 and the electrodes for connection to evaluation electronics.

[0060] Figure 14 schematically shows the arrangement of the pressure sensor from Figure 13 on a treatment head of a medical instrument, for example the treatment head of a laparoscopic instrument; and

[0061] Figure 15 shows a schematic representation of the steps of a

[0062] Manufacturing process.

[0063] Detailed description Preferred embodiments are described below with reference to the figures. Identical, similar, or equivalent elements in the different figures are designated with identical reference numerals, and repeated descriptions of these elements are sometimes omitted to avoid redundancy.

[0064] Figures 1 to 9 show strain sensors in different configurations which can determine mechanical deformations of the underlying body, here in the form of a substrate 10, 12, 14.

[0065] A strain sensor is understood to be a sensor that detects a mechanical deformation of a body, for example a mechanical stretching or compression or a change in the surface tension of the body, and converts it into an electrically evaluable signal.

[0066] In the strain sensors presented here, the sensor elements that detect the mechanical deformation of the body are designed as nanogranular sensor elements 20. These nanogranular sensor elements 20 are each connected to the underlying material in such a way that a mechanical deformation of the underlying material causes the resistance of the nanogranular sensor element 20 to change in proportion to the mechanical deformation of the body. The change in the resistance of the nanogranular sensor element 20 allows conclusions to be drawn about the mechanical deformation of the underlying material.

[0067] The term "nanogranular sensor element" is used here to mean that the sensor element consists of, or at least comprises, a nanogranular material. Nanogranular materials offer the advantage that the measurable strain range of the sensor element can be precisely controlled by the shape, form, material, spacing, and number of grains within the sensor element. In particular, the grains can be embedded in a dielectric matrix. The various conductivity mechanisms arise, for example, from the different regimes of the conductivity phase diagram. For instance, thermally activated transport processes dominate in the Arrhenius regime, while different tunneling processes dominate in the inelastic and elastic co-tunneling regimes.In the granular Fermi fluid regime, metallic transport dominates, whereas in the universal behavior regime, conductivity is independent of specific system details.

[0068] In other words, a nanogranular sensor element comprises an ensemble of electrically conductive grains in the nanometer range, whose electrical transport properties are determined by their conductivity, size, spacing, and the matrix material. Sensitivity to temperature or radiation arises in particular from effects such as variable range hopping and thermally activated transport.

[0069] In other words, a material described in the literature as nanogranular comprises an ensemble of charge carrier centers that exist in different geometric configurations within at least one matrix material or a mixture of different matrix materials. These charge carrier centers can be distributed homogeneously or inhomogeneously within the matrix material. The electrical transport properties can be determined by material properties (charge carrier density, band structure, and, if applicable, electrical defects due to crystal flaws within the charge carrier centers), the geometric configuration of the charge carrier centers, and their spacing within the matrix.The physical properties of the matrix material (lattice configuration, crystal structure, material) and the individual transition between the matrix material and the individual charge carrier center (transition of the charge carrier center's ligand shell to the matrix, defects) also define the conductivity properties in the nanogranular material. Impurities in the charge carrier centers and in the matrix material also represent defects (essentially, all grain boundaries in the metal, in the matrix, and between the materials, as well as potentially between the materials themselves, are impurities) that are important for charge carrier transport. Furthermore, the interfaces of the nanogranular material with the continuum play a role in defining the conductivity.

[0070] The nanogranular sensor element 20 is deposited on the material of the body, for example, using the method described in Figure 15.

[0071] In the embodiments shown in Figures 1 to 9, the nanogranular sensor element 20 is arranged on the substrate 10, 12, 14 in such a position that, due to the mechanical connection between the nanogranular sensor element 20 and the underlying substrate, mechanical deformation or changes in the surface properties of the substrate 10, 12, 14 cause the dimensions of the nanogranular sensor element 20 to change along with the dimensions of the underlying surface or material. This mechanical change in the dimensions of the nanogranular sensor element 20 is accompanied by a change in its resistance.This change in resistance can be determined and from this change in resistance a conclusion can then be drawn about a mechanical compression or mechanical stretching or a change in the mechanical surface tension of the substrate 10, 12, 14 lying under the nanogranular sensor element 20.

[0072] For example, the substrate shown in Figures 1 to 4 can be configured as an (electrically) insulating substrate 10, an (electrically) non-insulating substrate 12, or a flexible substrate 14. The substrate 10 is schematically represented here as a silicon wafer, but it can also be a different material – in particular, the material of the body whose compression or stretching is to be determined.

[0073] Accordingly, the strain sensor 100, which is shown in a very schematic and sectional view in Figures 1 to 4, can either be arranged on a separate substrate, which in turn is arranged on a body to be monitored for its mechanical deformations, for example a component or an instrument, or the corresponding strain sensor 100 can be applied directly to the body of interest or to its substrate or to its material.

[0074] For example, the nanogranular sensor element 20 is intended to be applied directly to an insulating substrate 10. An insulating substrate 10 can be, for example, a plastic or another non-conductive material.

[0075] Furthermore, the nanogranular sensor element 20 can be applied to a non-insulating substrate 12, for example, a metal substrate. In this case, it may be necessary to apply an additional, thin insulating layer 60 directly to the non-insulating substrate 12. For example, the strain sensor 100 can be applied directly to a metal substrate in this way, with an interposed, very thin insulating layer 60 that does not significantly affect the behavior of the surface of the non-insulating substrate 12.

[0076] Thus, a strain sensor 100 can be applied at different positions on the insulating substrate 10, or non-insulating substrate 12, or flexible substrate 14 to monitor the mechanical behavior of the corresponding material, component or instrument.

[0077] The present disclosure accordingly provides strain sensors with nanogranular sensor elements 20 which are not only compact in size and have a very small mass, but can also be applied directly to a substrate.

[0078] For example, the size of the sensor element can be only 10nm x 10nm x 10nm, while the weight is only about 6x10 -21 The strain sensors, which measure in kg, are capable of handling small structural dimensions. Due to their small size, the strain sensors proposed here also offer high spatial resolution. In other words, the strain sensors can be positioned close together at different locations to specifically monitor the mechanical behavior of the underlying body at each position.

[0079] These advantages make the strain sensors proposed here suitable for a wide variety of applications that require precise and robust strain measurements.

[0080] With reference to Figure 1, a strain sensor 100 is now shown in a schematic cross-sectional view. The strain sensor 100 comprises a nanogranular sensor element 20, which is positioned on an electrically insulating substrate 10.

[0081] The width of the nanogranular sensor element 20 can be between 1 nm and 20 pm, preferably between 5 nm and 400 nm, for example 300 nm, and particularly preferably between 8 nm and 12 nm.

[0082] The height of the nanogranular sensor element 20 can be between 1 nm and 3 pm, preferably 5 nm to 400 nm, for example 300 nm or 6 nm.

[0083] The length of the nanogranular sensor element 20 can be between 1 nm and 20 pm, preferably between 5 nm and 400 nm, for example 300 nm, and particularly preferably between 8 nm and 12 nm.

[0084] The substrate 10 can, for example, also be an insulating, mechanically flexible substrate 14. In particular, the sensor element 20 is in direct contact with the electrically insulating substrate, which can be, for example, a polymer or a ceramic.

[0085] The sensor element 20 is electrically contacted by two electrodes 30 positioned on either side of the sensor element 20. These electrodes 30 enable the measurement of strain-dependent changes in the conductivity of the sensor element 20. In other words, if the dimensions of the sensor element 20 change due to mechanical deformation of the underlying substrate, its electrical conductivity or electrical resistance also changes. This change in conductivity can be measured via the contact by the electrodes 30 and provides a means of determining the change in the dimensions of the sensor element 20. In other words, the sensor element 20 is the element of the strain sensor 100 that responds in a defined manner to the dimensional change and thus dominates or enables the measurement.

[0086] The sensor element 20 and the electrodes 30 can be encapsulated in a cover layer 40. This cover layer 40 serves as a protective sheath and shields the sensor element 20 and the electrodes 30 from external environmental influences. In particular, external mechanical influences on the nanogranular sensor element 20 can be shielded in this way. The cover layer can also act as a thermal barrier, thus isolating the sensor element from parasitic thermal influences.

[0087] For the purposes mentioned above, the covering layer 40 can have a height between 1 nm and 3 pm, preferably between 25 nm and 400 nm. The height of the covering layer 40 is preferably set such that both the nanogranular sensor elements 20 and the electrodes 30 are completely covered by the covering layer 40.

[0088] This cover layer 40 thus ensures the stability and longevity of the strain sensor 100 and therefore enables long-term use in various applications and under harsh conditions.

[0089] With reference to Figure 2, a strain sensor 100 is shown in a second embodiment. In this embodiment, the sensor element 20 is positioned on an electrically non-insulating substrate 12. The electrically non-insulating substrate 12 can be a conductive material, such as a metal or a semiconductor. The electrically non-insulating substrate 12 can, for example, be a body in the form of a component of a device, such as a bolt of a mechanical connection, on which a strain measurement is to be performed.

[0090] In some cases, an insulating layer 60 is arranged between at least one of the electrodes 30 and the electrically non-insulating substrate 12. The insulating layer 60 serves to electrically isolate the electrode 30 from the electrically non-insulating substrate 12 and to reduce or prevent electrical interference from the electrically non-insulating substrate 12 that could potentially affect the measurement of strain-dependent conductivity changes of the sensor element 20. In this way, a short circuit between the electrodes 30 via the electrically non-insulating substrate 12 is also avoided.

[0091] Analogous to Figure 1, the nanogranular sensor element 20 is deposited onto the insulating layer 60 and the electrodes 30; in addition, the sensor element 20 and the electrodes 30 can also be encapsulated with a covering layer 40.

[0092] The insulating layer 60 is designed in particular such that it has no or no significant mechanical influence on the transmission of the mechanical deformation from the non-insulating substrate 12 to the nanogranular sensor element 20. In other words, the insulating layer 60 is designed so that it does not affect the measurement of the mechanical deformation of the body. The insulating layer 60 can, for example, have a thickness of 2–100 nm. Preferred materials for the insulating layer 60 are, for example, an oxide layer of the substrate such as SiOx or SixNy. TiN, CrN, aluminum oxide, or suitable polymers such as parylene can also be used as the insulating layer 60.

[0093] As shown in Figure 2, the insulating layer 60 can also be arranged below the sensor element 20. If the sensor element 20 has a lower specific resistance, i.e., a higher conductivity, than the substrate 10, then the insulating layer 60 below the sensor element 20 can be omitted. The conductivity ratio must be greater than the smallest measurable change in resistance of the sensor element 20. Accordingly, the conductivity ratio can be smaller if the conductivity of the sensor element 20 changes significantly than if it changes only slightly.

[0094] Referring to Figure 3, a strain sensor 100 is shown in a third embodiment. In this embodiment, the sensor element 20 is positioned on an electrically non-insulating substrate 12, analogous to Figure 2.

[0095] The sensor element 20 is electrically contacted by a first electrode 30, which is positioned on one side of the sensor element 20 and is insulated from the electrically non-insulating substrate 12 by an insulating layer 60. The sensor element 20 is in direct electrical contact with the electrically non-insulating substrate 12, which serves as a second electrode 30 for contacting the sensor element 20 to measure a change in conductivity.

[0096] Referring to Figure 4, a strain sensor 100 is shown in a fourth embodiment. In this embodiment, the sensor element 20 is positioned on an electrically non-insulating substrate 12, analogous to Figure 2. However, the first electrode 30 is applied to the sensor element 20, and the insulating layer 60 extends partially beneath the nanogranular sensor element 20.

[0097] Due to the small dimensions of the sensor element, precise electrode positioning is unnecessary, as the electrode can be applied as a film over the sensor element 20. This greatly simplifies the electrode structuring, since positioning accuracy of a few nanometers is not required to bring the sensor element 20 into contact with the electrodes 30. Various circuit arrangements of a strain sensor 100 are shown with reference to Figures 5A to 5C. In these configurations, the sensor element 20 is electrically connected to a first pair of electrodes 32 and a second pair of electrodes 34.

[0098] The first pair of electrodes 32 is connected to a voltmeter 70. The voltmeter 70 measures the voltage drop across the sensor element 20 between the contact areas with the electrodes 32.

[0099] A constant current source 72 is connected to the second pair of electrodes 34. The first pair of electrodes 32 lies between the second pair of electrodes 34.

[0100] The constant current source 72 supplies a stable, constant current that flows between the contact areas of the electrodes 34 and through the sensor element 20. This ensures a uniform voltage distribution within the sensor element 20.

[0101] The proposed contact and circuit configuration enables a voltage-correct measurement of the voltage using the voltmeter 70. The voltage varies with the mechanical dimension and therefore allows conclusions to be drawn about the strain change in the resistance of the sensor element 20. This setup allows for an accurate measurement of the resistance of the sensor element 20 and its strain-dependent changes.

[0102] In some embodiments, the sensor element 20 is deposited on the electrodes 30 such that it overlaps them at least partially. Figures 5A to 5C show different degrees of overlap between the sensor element 20 and the electrode pair 34. These varying degrees of overlap do not result in different voltage measurements at the inner pair of electrodes 32, thus enabling a stable manufacturing process.

[0103] Figure 6 shows a schematic diagram of the measuring circuit provided by the embodiment of the strain sensor 100 in Figures 5A to 5C. The sensor element 20 is connected to the first pair of electrodes 32 and the second pair of electrodes 34. The first pair of electrodes 32 lies within the second pair of electrodes 34 on the sensor element 20.

[0104] A voltmeter 70 is connected to the first pair of electrodes 32. The voltmeter 70 is designed to measure the voltage difference across the sensor element 20, which corresponds to the strain-dependent changes in the resistance of the sensor element 20. A constant current source 72 is connected to the second pair of electrodes 34. The constant current source 72 supplies a constant and stable current across the sensor element 20, ensuring a uniform voltage distribution within the sensor element 20. This arrangement enables an accurate measurement of the resistance of the sensor element 20 and its strain-dependent changes.

[0105] This circuit ensures a voltage-correct measurement.

[0106] With reference to Figure 7, a high-precision strain sensor 120 with a sensor element 20 is shown. The strain sensor 120 comprises a Wheatstone bridge 700 in which the sensor element 20 is embedded. The Wheatstone bridge 700 is a known electrical circuit used to measure an unknown electrical resistance by balancing two bridge arms, one of which contains the unknown component. In this case, the nanogranular sensor element 20 is the unknown resistance, the resistance of which changes in response to mechanical deformations.

[0107] The Wheatstone bridge 700 comprises four resistors: the nanogranular sensor element 20 with the first resistor R1 and three conventional resistors 76 with the second resistor R2, the third resistor R3 and the fourth resistor R4.

[0108] The nanogranular sensor element 20 exhibits a strain dependence of its resistance R1. The three other resistances R2, R3, R4 of the Wheatstone bridge 700 are formed by conventional resistors 76, which do not have such a dependence in their resistances. The three conventional resistors can be identical.

[0109] A constant current source 72 is connected to the Wheatstone bridge 700 to provide a stable current. A voltmeter 70 is connected across the bridge to measure the voltage changes corresponding to the strain changes detected by the sensor element 20. This setup ensures precise strain measurement by utilizing the Wheatstone bridge 700 for increased sensitivity and accuracy.

[0110] With reference to Figure 8, a high-precision strain sensor 130 in a configuration with a Wheatstone bridge 700 is shown. The Wheatstone bridge 700 comprises four resistors, designated R1, R2, R3, and R4. The nanogranular sensor element 20, connected by the electrodes 30, has a strain-dependent first resistance R1 and forms the first resistance of the Wheatstone bridge 700. The three other resistances R2, R3, and R4 of the Wheatstone bridge 700 are each formed by reference sensor elements 22. The reference sensor elements 22 can be manufactured by a process identical to that of the nanogranular sensor element 20 and also exhibit a strain dependency of their respective resistances R2, R3, and R4.

[0111] In the embodiment shown, the three reference sensor elements 22 are manufactured from the same material combination using the same method, so that the strain dependence of the three reference sensor elements 22 is identical or nearly identical.

[0112] A constant voltage source 74 is connected to the Wheatstone bridge 700. The constant voltage source 74 provides a stable voltage across the Wheatstone bridge 700. A voltmeter 70 is connected across the Wheatstone bridge 700 to measure the voltage difference, which enables a precise measurement of strain-dependent conductivity changes in the sensor elements 20. The voltage difference measured by the voltmeter 70 corresponds to the strain-dependent changes in the resistance of the sensor elements 20.

[0113] To obtain a highly accurate measurement of the strain-dependent resistance change in the strain sensor 130, the nanogranular sensor element 20 is preferably manufactured such that its resistance R1 exhibits a significant strain dependence in the relevant strain range. Preferably, however, the resistances R2, R3, R4 of the reference sensor elements 22 do not change.

[0114] This different behavior of the sensor element 20 and the reference sensor elements 22 with respect to the strain dependence of their respective resistances can be achieved by assembling the sensor element 20 and the reference sensor elements 22 from different materials and / or by post-processing them differently.

[0115] This different behavior of the nanogranular sensor element 20 and the reference sensor elements 22 can also be achieved by placing the reference sensor elements 22 in an area of ​​the substrate or the body to be measured that is not subject to any or less or different mechanical deformation.

[0116] With reference to Figure 9, a high-precision strain sensor 140 with a Wheatstone bridge 700 is shown. The Wheatstone bridge 700 comprises four resistors, designated R1, R2, R3, and R4. The sensor element 20, connected by the electrodes 30, forms the first resistor R1 of the Wheatstone bridge 700. A second sensor element 20 forms the opposite resistor R4 of the Wheatstone bridge 700. The two other reference sensor elements 22 form the resistors R2 and R3 of the Wheatstone bridge 700. The reference sensor elements 22 are manufactured from the same material combination using the same manufacturing process, so that the strain dependence of the reference sensor elements 22 is identical or nearly identical.

[0117] The two sensor elements 20 are manufactured from the same material combination using the same manufacturing process, so that the strain dependence of the sensor elements 20 is identical or nearly identical.

[0118] A constant voltage source 74 is connected to two of the nodes of the Wheatstone bridge 700. A voltmeter 70 is connected to the other two nodes via the Wheatstone bridge 700 to measure the voltage difference, which enables a precise measurement of strain-dependent conductivity changes of the sensor element 20.

[0119] To obtain a highly accurate measurement of the strain-dependent resistance change in the strain sensor 140, the sensor elements 20 are preferably manufactured such that their resistances R1, R4 exhibit a significant strain dependence in the relevant strain range. Preferably, in the same embodiment, the resistances R2, R3 of the reference sensor elements 22 do not change with respect to their resistances in the strain range of interest.

[0120] Due to the small dimensions of the sensor element, it is possible to provide a large number of Wheatstone bridges on the substrate, with each Wheatstone bridge being able to determine a strain range at its position with particular accuracy.

[0121] However, it is also possible that resistors R2 and R3 have a strain coefficient opposite to that of R1 and R4. This results in a particularly large measurement signal.

[0122] This different behavior of the sensor elements 20 and the reference sensor elements 22 with respect to the strain dependence of their respective resistances can be achieved by depositing the sensor elements 20 and the reference sensor elements 22 using different manufacturing processes and / or by post-processing the sensor elements 20 and the reference sensor elements 22 differently.

[0123] The sensor element 20 and the electrodes 30 can be encapsulated in a cover layer 40. This cover layer 40 serves as a mechanical and thermal protective housing and shields the sensor element 20 and the electrodes 30 from external environmental influences.

[0124] In some of the aforementioned cases, the nanogranular sensor element 20 is adapted with respect to its Coulomb barrier by post-irradiation. By adjusting the Coulomb barrier of the sensor element 20, the strain response of the sensor element 20 can be adapted so that it is suitable for the expected strain range of the substrate to be measured.

[0125] This adaptation can be achieved, for example, by applying a selected post-processing that leads to a specific crystallite size and spacing distribution, which in turn is specific to the Coulomb barrier for a material combination (charge carrier center & dielectric).

[0126] However, it is also possible that the manufacturing parameters used in the production process create sensor elements with a specific granularity, including a specific grain size and spacing. By adjusting the size and spacing, the Coulomb barrier can also be adjusted.

[0127] The basic design of the strain sensors 100 can also be used to build a pressure sensor 800.

[0128] The pressure sensor 800 is shown in a sectional view, for example, in Figure 10. Figure 11 shows a schematic representation of the interconnection of the nanogranular sensor elements 20 of the pressure sensor 800, and Figures 12 and 13 show schematic top-view representations of the layout of the circuitry of the pressure sensor 800.

[0129] Figure 10 shows a substrate 10, which is provided here in the form of an insulating substrate 10. The insulating substrate 10 can, for example, be a silicon wafer, which is provided in a known manner.

[0130] A cavity 82 is introduced into the insulating substrate 10 from the underside, which can be achieved, for example, by targeted etching of the insulating substrate 10. Etching the cavity 82 in the insulating substrate 10 results in only a thin membrane 80 remaining on the top side of the insulating substrate 10. The top side of the insulating substrate 10 can be, for example, silicon or silicon nitride (SiN).

[0131] To construct the pressure sensor 800, the cavity 82 is inserted into the insulating substrate 10, and the remaining membrane 80 then serves as a surface which, due to pressure fluctuations or pressure changes, undergoes a mechanical deformation of the surface, whereby the membrane 80 then, for example, bulges out or contracts when viewed from the outside.

[0132] The membrane 80 can, for example, be provided in such a way that it is relatively thin, for example in the range between 5 nm and 50 nm, preferably 8–12 nm, particularly preferably 10 nm. The membrane 80 can have a planar extent of 1–500 µm x 1–500 µm, preferably 25 pm x 25 pm. It is immediately apparent that these are very small dimensions, which, in particular with regard to the membrane thickness, are in the nanometer range.

[0133] The geometry of membrane 80 is shown schematically as rectangular or square in the figures, but is not limited to this. The shape of membrane 80 can also be round, elliptical, triangular, or organic.

[0134] Nanogranular sensor elements 20 are deposited on the upper surface of the membrane 80 and are contacted via associated electrodes 30. Figure 10 shows a cross-section through the four sensors, each comprising a nanogranular sensor element 20. In other words, the nanogranular sensor elements 20 lie in a plane or extend along a line spanning the membrane 80. This linear arrangement of the nanogranular sensor elements 20 on the membrane 80 is particularly evident in Figure 12.

[0135] The nanogranular sensor elements 20 are accordingly directly mechanically connected to the membrane 80 and can determine the mechanical deformations of the membrane 80 at the respective positions.

[0136] Figure 12 shows this setup again in a top view, again showing the insulating substrate 10 into which the square membrane 80 is inserted. The membrane 80 is formed by the cavity 82 shown in Figure 10 being introduced, in particular etched, from the back side (from the perspective of Figure 12). The square membrane 80 is covered with the nanogranular sensor elements 20, each of which is contacted via electrodes 30. The contacting of the nanogranular sensor elements 20 results in a circuit corresponding to the bridge circuit shown in Figure 11.

[0137] The sectional view in Figure 10 corresponds to a section through the nanogranular sensor elements 20 lying in a line from top to bottom, which are located virtually in the middle of the membrane 80.

[0138] By arranging the nanogranular sensor elements 20 along the extent of the membrane 80, it is possible to arrange two of the nanogranular sensor elements 20 at the edge region of the membrane 80, as shown, for example, by the nanogranular sensor elements 20 designated by the symbols R1 and R4 in Figures 10 and 12. The two nanogranular sensor elements 20 oriented more towards the center of the membrane 80, designated by the symbols R2 and R3, are connected accordingly, resulting in the circuit shown in Figure 11.

[0139] From the combined view of Figures 10 and 12, it also becomes apparent that the two nanogranular sensor elements 20 located more towards the edge, which are designated with the symbols R1 and R4, experience a different mechanical deformation of the membrane 80 when the membrane 80 is mechanically deformed than the nanogranular sensor elements 20 located in the middle of the membrane 80, which are designated with the symbols R2 and R3.

[0140] For example, mechanical deformation of the membrane 80 may result in stretching of the membrane 80 in the area of ​​the centrally located nanogranular sensor elements 20 with the symbols R2 and R3, whereas the nanogranular sensor elements 20 located at the edge with the symbols R1 and R4 experience less stretching or even compression. In other words, the mechanical deformation behavior of the membrane 80 depends on the position on the membrane 80 being considered.

[0141] In an alternative arrangement, for example, one or two of the nanogranular sensor elements 20, for example those designated by the symbols R2 and R3, can also be arranged outside the membrane 80 and, for example, in an area of ​​the substrate that is not deformed by the pressure change.

[0142] Although the sensors are shown exposed in Figure 10, a covering layer can also be applied above the sensors, as shown in Figures 1 to 4, to make the pressure sensor 800 particularly insensitive to external influences.

[0143] The pressure sensor in Figure 10 has a base layer 18 below the insulating substrate 10, which seals the cavity 82 at the bottom. The base layer 18 is preferably non-deformable by the pressures to be measured, so that an external pressure fluctuation only leads to a deformation of the membrane 80, but not to a deformation of the base layer 18.

[0144] The base layer 18 can be produced during the manufacture of the pressure sensor 800 by connecting, for example by bonding, the insulating substrate 10 to a base plate, which then forms the base layer 18. The base layer 18 can, for example, be a silicon wafer bonded to the silicon wafer of the substrate 10.

[0145] This bonding can also be carried out under vacuum conditions, so that a slight negative pressure relative to the atmosphere is provided in the cavity 82. In this way, the membrane 80 receives a slight preload in the direction of the cavity 82 and is therefore particularly sensitive and exhibits a defined mechanical behavior.

[0146] The design of the circuit as shown in Figure 11, namely via a bridge circuit, results in the nanogranular sensor elements 20, which are arranged diagonally to each other in the circuit, mutually reinforcing each other, so that a particularly good readout of the signal can be achieved.

[0147] By interconnecting the nanogranular sensor elements 20 in the proposed manner, undesirable influences can also be compensated for. For example, temperature influences on the nanogranular sensor elements 20 can be compensated for, so that only the respective mechanical deformations of the membrane 80 lead to a change in the signal and pressure changes can thus be reliably read out.

[0148] Figure 14 schematically shows a medical instrument 180 in which a pressure sensor 800 is integrated or on which a pressure sensor 800 is arranged.

[0149] Medical Instrument 180 can, for example, be configured to perform thermal treatment procedures and may be, for instance, the treatment head of a coagulator, an electrocautery device, a plasma coagulator, a plasma ablation instrument, a laser ablation instrument, or a resection instrument. Medical Instrument 180 may be designed, for example, as a laparoscopic or minimally invasive instrument, but may also have other form factors.

[0150] The medical instrument 180 can also be used for primarily mechanical procedures, such as forceps, scissors, or a scalpel. The pressure sensor measures the pressure applied to the medical instrument 180.

[0151] The medical instrument 180 can also alternatively or additionally have one or more strain sensors, as described above in relation to Figures 1 to 9. This is particularly important if the medical instrument 180 is designed to exert mechanical forces on the patient for treatment—for example, if the medical instrument 180 is forceps, scissors, or a scalpel. The strain sensors allow conclusions to be drawn about the forces exerted on the patient or the surgical area, so that these forces can be documented, limited, or increased. For example, a surgeon can thus receive feedback on the forces exerted in order to remain within a predetermined range of forces to be applied.

[0152] The exemplary medical instrument 180 includes a treatment head 182, which is set up to carry out the treatment procedure.

[0153] The treatment head 182 is connected to an elongated handle 184 or a holder for operation, for example by the surgeon. The pressure sensor 800 is integrated into the treatment head 182 or provided directly on it, so that it can determine the pressure present in the vicinity of the treatment head 182.

[0154] In various implementations, the medical instrument 180 can be designed for minimally invasive procedures, with the pressure sensor 800 providing real-time pressure data. This data can be used, for example, to control or regulate a supply device that provides pressure to the medical instrument 180. The compact nature of the pressure sensor 800, based on nanogranular sensor elements 20, allows for integration into various types of medical instruments or devices without significantly altering their form factor or functionality.

[0155] In some aspects, the style 184 of the medical instrument 180 can internally accommodate up to four connecting cables 38 to enable the interconnection and contacting of the different pressure sensors 100 proposed above.

[0156] In some aspects, the internal resistance of the nanogranular sensor element 20 can be set so high that the use of very thin connecting cables becomes possible, thus enabling a very slim design of the medical instrument.

[0157] Figure 15 shows a schematic representation of the manufacturing process using electron beam induced deposition (EBID) of the nanogranular sensor element. This manufacturing process enables the strain sensor to be seamlessly applied to or integrated into various substrates, thereby increasing its adaptability in diverse applications.

[0158] For example, the nanogranular sensor elements 20 shown in Figures 1 to 14 can be generated using EBID.

[0159] In a first step S1, a substrate is therefore provided in the coating system.

[0160] In a second step S2, a precursor gas is introduced in the immediate vicinity of the electron beam focus, with the electron beam focus located on the substrate surface. In a third step S3, which can also precede the first step in the sequence of events, electrodes can be pre-structured on the substrate surface using standard lithography techniques, so that the sensor element is applied to the electrodes.

[0161] However, it is also possible that the electrodes are applied to the substrate only after the sensor element has been manufactured, so that the third step S3 is temporally after the fourth step S4 described below.

[0162] In a fourth step S4, the substrate is described by guiding the electron beam over the substrate in a raster pattern.

[0163] However, it is also possible that the sensor elements 20 are manufactured using pulsed laser deposition. Laser evaporation processes are also conceivable, for example, cluster deposition processes of clusters on the order of a few nanometers, or sputtering processes, in particular co-sputtering processes, in which the components of the sensor element are simultaneously deposited onto the substrate.

[0164] In the above methods, the local sensor elements can be created by appropriately masking the substrate before the coating process.

[0165] In a fifth step S5, the nanogranular sensor elements 20 can be post-processed, in particular post-irradiated, which allows the Coulomb barrier of the nanogranular sensor element 20 to be adjusted.

[0166] The various strain sensor configurations revealed here are industrially applicable due to their versatile and adaptable design across a wide range of industries. The sensor's compact size and high spatial resolution make it suitable for precise strain measurements in diverse applications.

[0167] The encapsulation of the sensor element and electrodes in a biocompatible covering layer ensures that the strain sensor can be safely used in contact with the skin or inside the body without risk of adverse reactions. This protective layer also helps maintain the integrity of the sensor during sterilization processes, ensuring that it remains a sterile and safe tool for medical use.

[0168] Where applicable, all individual features illustrated in the exemplary embodiments can be combined and / or interchanged without departing from the scope of the invention. List of reference symbols

[0169] 10 insulating substrate

[0170] 12 non-insulating substrate

[0171] 14 flexible substrate

[0172] 16 outer functional layer(s)

[0173] 18 soil layer

[0174] 20 nanogranular sensor element

[0175] 22 Reference sensor element

[0176] 30 electrode

[0177] 32 first pair of electrodes

[0178] 34 second pair of electrodes

[0179] 38 connection cables

[0180] 40 Cover layer

[0181] 60 Insulation layer

[0182] 70 Voltmeter

[0183] 72 Constant current source

[0184] 74 Constant voltage source

[0185] 76 conventional ohmic resistance

[0186] 700 bridge circuit

[0187] 80 Membran

[0188] 82 cavity

[0189] 800 pressure sensor with diaphragm

[0190] 100 strain sensors

[0191] 120 strain sensor

[0192] 130 strain sensor

[0193] 140 Strain gauge 180 Medical instrument

[0194] 182 Treatment head of the medical instrument

[0195] 184 Style of medical instrument

[0196] R1, R2, R3, R4 resistors in the Wheatstone bridge

Claims

Claims 1. Pressure sensor (800) comprising: a substrate (10, 12, 14) with a pressure-sensing membrane (80); at least one nanogranular sensor element (20) deposited on the membrane (80); at least two electrodes (30, 12) electrically connected to the sensor element (20) to enable the measurement of pressure-induced conductivity changes of the sensor element (20).

2. Pressure sensor (800) according to claim 1 , characterized in that the membrane (80) delimits a cavity (82) introduced into the substrate (10, 12, 14), which is preferably gas-tight sealed against the environment and in which a negative pressure relative to the environment is particularly preferably present.

3. Pressure sensor (800) according to one of the preceding claims, characterized in that the membrane (80) has a planar extent of 1 - 500pm by 1 - 500pm, preferably 25pm by 25pm and / or the membrane (80) has a thickness in a range between 5 nm and 50 nm, preferably 8-12 nm, particularly preferably 10 nm.

4. Pressure sensor (800) according to one of the preceding claims, characterized in that at least four nanogranular sensor elements (20) are deposited on the substrate; wherein two of the nanogranular sensor elements (20) are deposited in a region within the membrane (80) and form a second bridge resistor (R2) and a third bridge resistor (R3); the two further nanogranular sensor elements (20) form a first bridge resistor (R1) and a fourth bridge resistor (R4); and the four bridge resistors (R1, R2, R3, R4) are connected via a bridge circuit (700).

5. Pressure sensor (800) according to claim 4, characterized in that the two further nanogranular sensor elements (20) are deposited in the region of the edge of the membrane (80) and form the first bridge resistor (R1) and the fourth bridge resistor (R4).

6. Pressure sensor (800) according to claim 4 or 5, characterized in that the four nanogranular sensor elements (20) are arranged in a plane traversing the membrane (80) and / or along a line passing through the membrane (80).

7. Pressure sensor (800) according to one of the preceding claims, characterized in that the width of each nanogranular sensor element (20) is between 1 nm and 500 nm, preferably between 200 and 400 nm, particularly preferably between 8 nm and 12 nm and / or the height of each nanogranular sensor element (20) is between 1 nm and 100 nm, preferably 1 nm to 12 nm and / or wherein the length of each nanogranular sensor element (20) is between 1 nm and 100 nm, preferably 8 nm to 12 nm.

8. Strain sensor (100, 120, 130, 140), comprising: a substrate (10, 12, 14); a nanogranular sensor element (20) deposited on the substrate (10, 12, 14); at least two electrodes (30, 12) electrically connected to the sensor element (20) to enable the measurement of strain-dependent conductivity changes of the sensor element (20).

9. Strain sensor according to claim 8, characterized in that the width of the sensor element (20) is preferably between 1 nm and 500 nm, preferably between 200 and 400 nm, particularly preferably between 8 nm and 12 nm, and / or wherein the height of the sensor element (20) is between 1 nm and 100 nm, preferably 1 nm to 12 nm, and / or wherein the length of the sensor element (20) is between 1 nm and 100 nm, preferably 8 nm to 12 nm.

10. Strain sensor according to claim 8 or 9, characterized in that the sensor element (20) is in direct contact with the substrate (12, 14), wherein an insulating layer (60) is arranged between a first electrode (30) and the substrate (12, 14) and wherein the electrically non-insulating substrate (12, 14) preferably forms a second electrode (30).

11. Strain sensor according to one of claims 8 to 10, characterized in that the sensor element (20) is encapsulated with a cover layer (40).

12. Strain sensor according to one of claims 8 to 11, characterized by a Bridge circuit (700), wherein at least one sensor element (20) is a measuring resistor.

13. Strain sensor according to claim 12, characterized in that the bridge circuit (700) is a 1 / 4 bridge, a 1 / 2 bridge or a 4 / 4 bridge.

14. Method for manufacturing a strain sensor (100, 110, 120, 130, 140, 150, 160, 170), the method comprising: Providing a substrate (10, 12, 14); Providing at least two electrodes (30); Deposition of a nanogranular sensor element (20) on the substrate (10, 12, 14); and connection of the sensor element (20) to the at least two electrodes (30) to enable the measurement of strain-dependent conductivity changes of the sensor element (20).

15. Method according to claim 14, characterized in that the step of depositing the sensor element (20) comprises the following steps: Masking the deposition site for the sensor element (20); Deposition of the sensor element using pulsed laser deposition and / or laser evaporation and / or cluster deposition and / or sputtering and / or co-sputtering; and removal of the masking.

16. Method according to claim 14 or 15, characterized in that the step of depositing the sensor element (20) comprises the following steps: Local deposition of the sensor element (20) by means of Electron Beam Induced Deposition (EBID) or Focused Ion Beam Deposition.

17. Method according to one of claims 14 to 16, characterized in that the deposited sensor element (20) is post-processed, preferably by changing the crystal structure and / or grain structure, wherein the temperature with the maximum conductivity change is particularly preferably shifted into a temperature measurement range.

18. Method according to claim 17, characterized in that the post-processing includes or is annealing, in particular local laser annealing.

19. Medical instrument (180) comprising: a treatment head (182) for treating a patient; and a pressure sensor (800) arranged on the treatment head (182) according to any one of claims 1 to 7 and / or a strain sensor (100) according to any one of claims 8 to 13.

20. Medical instrument (180) according to claim 18, characterized in that the nanogranular sensor element (20) is deposited directly on the treatment head (182) as a substrate.

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